The historical data necessary for defining baselines for how ecosytems have changed are missing from almost all marine coastal systems. However, remarkably broad and uniquely detailed historical data do exist for US coastal region. One hundred years ago an incredibly comprehensive study was conducted in southern New England. Unlike any other, this study provides us with a singularly unique window on the biodiversity of marine coastal habitats prior to modern coastal development, most species invasions, and recent climate change. The study was done between 1903 and 1907 and is based on over 450 dredge samples collected in Buzzards Bay and Vineyard Sound. All samples were analyzed for invertebrates, macroalgae, sea grasses, and fish and the report includes information on over 2000 marine species occurring in the region . The geographic location, depth and bottom substrate type of all sites were recorded making detailed mapping of habitat and organism distributions possible. This century-old study provides incredible detail on the historical status of marine biodiversity within a broad region of more than 1300 km2.